1. Field of the Invention
The present invention relates to capsule endoscopes capable of floating in liquid, for example, introduced into a subject and obtaining an in-vivo image.
2. Description of the Related Art
In recent years, capsule endoscopes having an imaging function and a radio communication function have appeared in the filed of endoscopes. A capsule endoscope of this type is typically configured to, for observation (examination), move inside the internal organs such as esophagus, stomach, and small intestine (within body cavities) by the organs' peristaltic movement during an observation period, after the endoscope is swallowed from a mouth of a person to be tested as a subject (human body) until the endoscope is naturally excreted from the body of the person to be tested, and sequentially take images using the imaging function.
International Publication No. 02/95351 (Japanese Patent Application Laid-Open No. 2004-529718) discloses a technique suitable for an observation of large intestine in which a capsule endoscope is swallowed together with liquid and floats in the liquid by making the specific gravity of the capsule endoscope same as that of liquid surrounding the endoscope or 1 which is the same as the specific gravity of water, so that the capsule endoscope can quickly reach the large intestine. Moreover, according to International Publication No. 02/95351, addressing the fact that only a portion close to the capsule endoscope can be observed when the capsule endoscope is close to a wall surface of a body cavity, it is possible to secure an observation view by making an observation with the capsule endoscope floating in the liquid, and thus realize the observation without an oversight. Japanese Patent Application Laid-Open No. 2004-121733 also refers to an observation in water.